Ruckerhill Jacks



(Thanks to Gaye Redpath-Schaeper at Conquest Terriers for assembling this list)

Note: The Jack Russell Health Registry / Research Foundation in  conjunction with the University of Missouri are working to find the genetic markers for the more serious mutations affecting the Jack Russell and provides a listing of dogs submitted by their owners and breeders for tested genetic information. These are responsible breeders that are trying to keep their breeding lines healthy and are trying to breed away from the identified genetic exposures. The following is an explanation of what the DNA test results mean to the health of the tested dog:  

Normal - This dog has DNA tested clear for the mutation known to cause the issue . This dog can only transmit a normal gene to its offspring and can be bred to a dog with any test result with NO risk of producing AFFECTED offspring.

Normal by Descent - This dog's Sire & Dam have both DNA Gene tested clear for the mutation known to cause the issue and can only carry a normal set of gene's. This dog can only transmit a normal gene to its offspring and can be bred to a dog with any test result with NO risk of producing AFFECTED offspring.

Carrier - This dog has DNA tested as a carrier for the mutation known to cause the issue. It is far less likely to develop the clinical symptoms of the issue than an affected dog. This dog may transmit either a normal gene or an affected gene to it's offspring. Therefore this dog should only be bred to a normal dog to prevent producing an affected puppy. Breeding this dog to a normal will produce ~50% normal and ~50% carrier pups in the litter.

Affected/At Risk - This dog has DNA tested as Affected for the mutation known to cause the issue. It is at risk for developing the clinical symptoms of the issue at some point in it's lifetime. There is no way to predict when or even if the symptoms may appear. This dog can only pass an affected gene to it's offspring and if bred should only be bred to a normal dog so that there would only be the possibility of carriers and not affected pups in the litter...


  1. Cataract: Lens opacity which obscures vision and may cause blindness.
  2. Congenital Cataract and Microphthalmia: Cataracts associated with a small eye globe.
  3. Distichiasis: Abnormal location of eyelashes on the margin of the eyelid, causing irritation.
  4. Glaucoma: Increased pressure in the globe which can damage the eye causing blindness.
  5. Glaucoma (pigmentary): Glaucoma in which a dark pigment is also present in the globe and which apparently blocks the drainage angle.
  6. Lens Luxation (PLL): Dislocation of the lens from its normal site behind the cornea (partial or complete). DNA Marker found and dog can be identified as Normal, Carrier, or Affected - all breeding stock should be tested and not used if Affected.
  7. Persistent Pupillary membranes: Failure of blood vessels in the anterior chamber to regress normally; there may be impaired vision or blindness.
  8. Progressive Retinal Atrophy: Degeneration of the retinal vision cells which progresses to blindness.
  9. Trichiasis: Abnormal placement of the eyelashes on the eyelid.


  1. Cerebellar Ataxia (SCA): Degeneration of the cortex of the cerebellum leading to a staggering gait; it may or may not progress. DNA Marker found and dog can be identified as Normal, Carrier, or Affected - all breeding stock should be tested and not used if Affected.
  2. Congenital Myasthenia Gravis: Severe muscle weakness may cause megaesophagus, fatigue and collapse due to a failure of neuromusculartransmission of nerve impulses.
  3. Bilateral Deafness: Inability to hear; i.e., completely deaf, both ears affected.
  4. Unilateral Deafness: Partial deafness; one ear affected.
  5. Epilepsy: Seizures commonly called fits; they recur generally closer together.
  6. Hydrocephalus: Accumulation of fluid in the brain causing severe pressure and degeneration of the brain.
  7. Myelodysplasia: Lack of development of the brain causing incoordination.
  8. Scotty Cramp: Muscle cramps triggered by excitement or exercise; you may see a rabbit hopping gait.
  9. Trembling: Excessive shaking or trembling, particularly of the rear limbs.
  10. Wobbler Syndrome: Abnormality of the neck vertebrae causing rear leg ataxia which may progress to paralysis.
  11. Ceroid-Lipofuscinosis (ATP subunit C storage): Causes night blindness, confusion, unpredictable aggressiveness, and ataxia late in the course of the disease.
  12. Ceroid-Lipofuscinosis: Causes visual impairment, confusion, erratic temperaments, and apparent loss of memory for previously learned tasks.
  13. Congenital Vestibular Disease: Causes loss of balance/incoordination, dog appears to try to keep from falling.
  14. DEGENERATIVE MYELOPATHY: (DM) a disease which causes spinal cord deterioration and progressive loss of function. Clinical signs begin to appear in older dogs – most are 8-10yrs or older, but onset at age 7 and as late as 15yrs has been documented. Onset and progression of clinical signs is subtle, and the dog is not painful. The first clinical signs typically observed are dragging of the hind toes and hind limb weakness, progressing over several months to muscle wasting and a complete loss of control of hind limbs. Because this is an old dog disease - many dogs that are affected pass prior to showing any clinical signs of the issue.


  1. Achondroplasia (Appendicular): Lack of normal development of the skeleton, particularly of the appendages (limbs); dwarfism.
  2. Cleft Lip/Cleft Palate: A fissure in the roof of the mouth and upper lip, may be present together or separately.
  3. Hemivertebra: Abnormal formation of the body of the vertebra, can cause posterior ataxia and paralysis. It causes the twisted tail in the screw tailed breeds.
  4. Legg-Perthes: Aseptic necrosis of the head and neck of the femur, causes rear leg lameness.
  5. Overshot: Upper jaw extends beyond the lower jaw.
  6. Patellar Luxation: Poor development of structures holding patella (knee cap) in place, usually medial (inward) in small breeds. This can also be caused by enviormental factors as slippery floors and falls. 
  7. Premature Closure of the Ulna: Ulna stops growing sooner than radius, causes wrists to turn in and front feet to turn out.
  8. Radial Agenesis: Radius stops growing sooner than the ulna causing bowed front legs.
  9. Undershot: Lower jaw extends beyond the upper jaw.


  1. Laryngeal Hypoplasia: Failure of development of the larynx (voice box) causing breathing difficulties.
  2. Tracheal Collapse: Improper formation of cartilaginous rings of the trachea causing mild to severe breathing problems.
  3. Tracheal Hypoplasia: A small trachea due to improper development causes mild to severe breathing difficulties.


  1. Oligodontia: Absence of most if not all teeth.
  2. Pyloric Stenosis: Abnormally small opening between the stomach and the duodenum, prevents food from passing and causes sharp projectile vomiting.


  1. Aggressiveness (Excessive): Excessively assertive or forceful with other dogs or people, may attack or bite without reasonable provocation.


  1. Von Willebrand’s Disease: Reduced factor VIII in the blood resulting in a prolonged bleeding time; may be mild, moderate, or severe and can cause death.


  1. Cardiomyopathy: Abnormality of heart muscle may cause edema of the lung, weakness at exercise and sudden death.
  2. Patent Ductus Arteriosus: Failure of the fetal vessel between the aorta and pulmonary artery to close around the time of birth, causes heart murmurs, exercise weakness, and may cause death.


  1. Inguinal Hernia: Outpouching of skin in the area of the inguinal ring which may contain viscera; a scrotal hernia is a type of inguinal hernia.
  2. Umbilical Hernia: Outpouching of skin over belly button; may contain abdominal viscera, and regress spontaneously.


  1. Diabetes Mellitus: Excessive sugar in the blood and urine due to a lack of insulin.
  2. Growth Hormone Deficiency: Lack of production of or inability to use growth hormone causes dwarfism.
  3. Hypothyroidism: Destruction of the thyroid gland due to an attack from the animal’s own immune system causes rough, scaly skin; hair loss; weight gain.


  1. Cryptorchidism: Absence of testicles due to retention in the abdomen or inguinal region, may be one or both sided or may slide in and out of the scrotum.
  2. Hermaphrodite: Presence of gonadal tissue for both sexes due to the presence of a full compliment of both male and female chromosomes.


  1. Short or “High” Toes. This is a developmental condition where the outside toes, usually on one or both front feet, do not grow to normal length, giving the appearance of being a “short” or “high” toe that does not touch the ground when full the terrier is full grown.
  2. Absence of premolars (one or more). Terrier is missing one or more pre-molars; does not have full denture.
  3. Leptospirosis: Lepto is a disease that can occur anywhere, but is more common in areas with heavy rainfall, it is a zoonotic disease, meaning it can be spread from animals to people. It is a highly contagious bacterial infection of the kidney that is transmitted through the urine of an infected animal. Pets that come into contact with infected urine, urine-contaminated soil, water, food or bedding are at risk. Dogs can be infected by exposure of Lepto to the mucus membranes or an unhealed break in the skin. Wild animals particularly raccoons, skunks, rats, farm animals, rodents, sea lions and other dogs are common carriers. Fever, depression, sore joints, and blood in urine can be indicators… A vaccine is available but should be administered separate from other immunizations and after 6 months of age - the vaccine may not prevent contracting the disease but may lessen the long term effects (undetermined).
  4. Anaplasmosis:  A tick-borne disease caused by bacteria transmitted to dogs, humans and other animals primarily caused by bites from the black-legged tick or brown dog tick.
  5. Ehrlichiosis: A bacterial illness transmitted to dogs, humans and other animals by ticks that causes flu-like symptoms. The lone star tick is the primary source of this disease.
  6. Lyme disease: The most common of tick-borne diseases, Lyme disease is a bacterial illness that can be transmitted to dogs, humans and other animals. The primary carrier is the deer tick or bear tick.